Hi, I am so sorry to bother you again, but I went onto airtran's website and this is what it said:

Can I travel with a pet?

We accept small, domesticated cats, dogs and birds that will fit in an approved carrier under the seat.

The pet kennel is limited to maximum dimensions of 8.5 inches high x 17 inches long x 12 inches wide.
The carrier must be leak proof and ventilated on at least two sides.
There is no weight restriction on pets.
The pet must remain in the carrier and under the seat for the duration of the flight.
this is what the other airlines say too. Do you know if that person who brought their guinea pig told the airline that it was a guinea pig? or did they say it was another type of pet and got through?

It sucks! They are adorable. I wish I could help her find a place for them. I'd take them too, because they are cute. I asked permission to show the photo's here!

They kinda look like abby's with the hair sticking out, but not as long. One is the color of Edward, and the other's colors match Alexander, but in a row, from front to back tan, white and black. So cute!